Orientation of capture antibodies on gold nanoparticles to improve the sensitivity of ELISA-based medical devices.

The sensitivity of ELISA-based devices strongly depends on the right orientation of antibodies on the sensor surface. The aim of this work was to increase the analytical performance of a commercial ELISA-based medical device (VIDAS®), thanks to the specific orientation of antibodies on gold nanostructured disposables. For this purpose, fPSA VIDAS® assay was used as model and the disposable providing the antigen binding surface (SPR®) was functionalized with gold nanostructures coated with monovalent half-fragment antibodies (reduced IgG, rIgG). The functionalization of polystyrene SPRs® with gold nanostructures was achieved through a one-step incubation of gold dispersions in a mixture of non-toxic solvents. Five different concentrations of gold nanoparticles (NPs) were tested with a maximum fluorescence enhancement for NPs density around 3-8 *103 NPs/µm2 (752 ± 11 RFV vs 316 ± 5 RFV of bare SPRs®). The comparison of the dose-response curve obtained with commercial and gold coated-SPRs® revealed a significant improvement (p < 0.0001) of the analytical sensitivity of the VIDAS® system using nanostructured disposables. This improved version of SPRs® allows to distinguish small variations of fPSA concentrations opening the way to the application of this biomarker to other kinds of cancer as recently described in the literature.

Association of ventilator-free days with respiratory physiotherapy in critically ill patients with Coronavirus Disease 2019 (COVID-19) during the first pandemic wave. A propensity score-weighted analysis.

Background: Respiratory physiotherapy is reported as safe and feasible in mechanically ventilated patients with severe Coronavirus Disease (COVID-19) admitted to Intensive Care Unit (ICU), but the short-term benefits remain unclear. Methods: We performed a retrospective observational study in four ICUs in Northern Italy. All patients with COVID-19 admitted to ICU and under invasive mechanical ventilation (MV) between March 1st and May 30th, 2020, were enrolled into the study. Overlap weighting based on the propensity score was used to adjust for confounding in the comparison of patients who had or had not been treated by physiotherapists. The primary outcome was the number of days alive and ventilator-free (VFDs). The secondary outcomes were arterial partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio (P/F) at ICU discharge, ICU length of stay, ICU and hospital mortality, and survival at 90 days. The trial protocol was registered on clinicaltrials.gov (NCT05067907). Results: A total of 317 patients were included in the analysis. The median VFDs was 18 days [interquartile range (IQR) 10; 24] in patients performing physiotherapy and 21 days (IQR 0; 26) in the group without physiotherapy [incidence rate ratio (IRR) 0.86, 95% confidence interval (CI): 0.78; 0.95]. The chance of 0 VFDs was lower for patients treated by physiotherapists compared to those who were not [odds ratio (OR) = 0.36, 95% CI: 0.18-0.71]. Survival at 90 days was 96.0% in the physiotherapy group and 70.6% in patients not performing physiotherapy [hazard ratio (HR) = 0.14, 95% CI: 0.03-0.71]. Number of VFDs was not associated with body mass index (BMI), sex, or P/F at ICU admission for individuals with at least 1 day off the ventilator. Conclusion: In patients with COVID-19 admitted to ICU during the first pandemic wave and treated by physiotherapists, the number of days alive and free from MV was lower compared to patients who did not perform respiratory physiotherapy. Survival at 90 days in the physiotherapy group was greater compared to no physiotherapy. These findings may be the starting point for further investigation in this setting.

Time to active sitting position: One-year findings from a temporary COVID-19 intensive care unit.

OBJECTIVE: To investigate the association between time to active sitting position and clinical features in people with COVID-19 admitted to intensive care unit (ICU) and referred to physiotherapists. METHOD: Prospective study conducted in the largest temporary ICU in Lombardy (Italy) between April 2020 and June 2021. All individuals with COVID-19 who received physiotherapy were included. Multivariable Cox proportional hazard model was fitted to explore the statistical association between active sitting position and characteristics of patients referred to physiotherapists, also accounting for the different multidisciplinary teams responsible for patients. RESULTS: 284 individuals over 478 (59.4%) had access to physiotherapy, which was performed for a median of 8 days, without difference between multidisciplinary teams (P = 0.446). The active sitting position was reached after a median of 18 (IQR: 10.0-32.0) days. Sex was the only characteristic associated with the time to active sitting position, with males showing a reduced hazard by a factor of 0.65 (95% CI: 0.48-0.87; P = 0.0042) compared to females. At ICU discharge, nearly 50% individuals increased Manchester Mobility Score by 3 points. During physiotherapy no major adverse event was recorded. CONCLUSION: Individuals with COVID-19 take long time to reach active sitting position in ICU, with males requiring longer rehabilitation than females.

Safety and feasibility of physiotherapy in ICU-admitted severe COVID-19 patients: an observational study.

Early physiotherapy could play an important role in the management of severe COVID-19 subjects with consequences of prolonged ICU stay, although its effectiveness is still unclear. Aim of this study is to describe physiotherapy performed in severe COVID-19 patients and to evaluate its safety and feasibility. Consecutive adults with confirmed SARS-CoV-2 infection, admitted to the ICU, needing invasive mechanical ventilation for >24 hours and receiving early physiotherapy, have been enrolled. Adverse events occurred during physiotherapy sessions and timing and type of physiotherapy delivered were analysed, to identify the interventions most frequently performed and to determine the time taken to first mobilize, stand and walk. Functional and clinical assessment of patients was also performed at hospital discharge. Eighty-four severe COVID-19 subjects were enrolled. Few minor adverse events were recorded. Active mobilization was promoted over passive mobilization and independence in daily life activities was supported. Time interval from patients' intubation to the first physiotherapy treatment was 13 days and to walking was 27 days. Forty-eight (57.1%) subjects returned at home, whereas 29 (34.5%) were discharged to in-patient rehabilitation. Patients with tracheostomy experienced a delay in time from ICU admission until sit out of bed and ambulation, if compared with subjects without tracheostomy, although no differences were found in 6MWT and 1m-STST performances. This study reporting early physiotherapy during pandemic suggests that this intervention is feasible and safe for severe COVID-19 subjects, as well as healthcare workers, although delayed compared to other critically ill patients.

Muscle strength and functional outcome after prone positioning in COVID-19 ICU survivors.

OBJECTIVE: To evaluate the muscle strength and functional level of patients discharged from intensive care unit (ICU) in relation to the swimmer position as a nurse intervention during pronation. METHODS: Prospective study conducted in the hub COVID-19 center in Milan (Italy), between March and June 2020. All patients with COVID-19 discharged alive from ICU who received invasive mechanical ventilation were included. Forward continuation ratio model was fitted to explore the statistical association between muscle strength grades and body positioning during ICU stay. RESULTS: Over the 128 patients admitted to ICU, 87 patients were discharged alive from ICU, with available follow-up measures at hospital discharge. Thirty-four patients (39.1%) were treated with prone positioning as rescue therapy, for a total of 106 pronation cycles with a median duration of 72 (IQR 60-83) hours. Prone positioning did not influence the odds of showing particular level of muscle strength, in any of the evaluated districts, namely shoulder (OR 1.34, 95%CI:0.61-2.97), elbow (OR 1.10, 95%CI:0.45-2.68) and wrist (OR 0.97, 95%CI:0.58-1.63). Only in the shoulder district, age showed evidence of association with strength (OR 1.06, 95%CI:1.02-1.10), affecting people as they get older. No significant sequalae related to swimmer position were reported by physiotherapists or nurses. CONCLUSION: Swimmer position adopted during prone ventilation is not associated with worse upper limb strength or poor mobility level in COVID-19 survivors after hospital discharge.

Physiotherapy approach after lung transplantation in a critically ill COVID-19 patient: a case report.

This study describes the case of an 18-years-old male affected by severe COVID-19, who was receiving bilateral lung transplantation (LT), after 71 days of mechanical ventilation and 55 days of veno-venous extracorporeal membrane oxygenation. From post-operative day 2, early mobilization and physiotherapy treatments were performed. Weaning from mechanical ventilation, the use of non-invasive ventilation and tracheostomy management were included in the treatment. Forty-five days after LT the patient was discharged at home, showing improvements in terms of functional and respiratory parameters, quality of life and mood. While evidences about physiotherapy treatments in lung transplantation post severe COVID-19 remain limited, early approach and a multidisciplinary team may be considered key elements for functional recovery of these subjects.

Portable High-Flow Nasal Oxygen during Walking in Patients with Severe Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial.

BACKGROUND: High-flow nasal oxygen (HFNO) improves exercise capacity, oxygen saturation, and symptoms in patients with chronic obstructive pulmonary disease (COPD). Due to the need of electricity supply, HFNO has not been applied during free ambulation. OBJECTIVE: We evaluated whether HFNO delivered during walking by a battery-supplied portable device was more effective than usual portable oxygen in improving exercise capacity in patients with COPD and severe exercise limitation. The effects on 6-min walking tests (6MWTs) were the primary outcome. METHODS: After a baseline 6MWT, 20 stable patients requiring an oxygen inspiratory fraction (FiO2) <0.60 during exercise, randomly underwent 2 6MWT carrying a rollator, under either HFNO with a portable device (HFNO test) or oxygen supplementation by a Venturi mask (Control) at isoFiO2. Walked distance, perceived dyspnea, pulse oximetry, and inspiratory capacity at end of the tests as well as patients' comfort were compared between the tests. RESULTS: As compared to baseline, walked distance improved significantly more in HFNO than in the control test (by 61.1 ± 37.8 and 39.7 ± 43.8 m, respectively, p = 0.01). There were no significant differences between the tests in dyspnea, peripheral oxygen saturation, or inspiratory capacity, but HFNO test was appreciated as more comfortable. CONCLUSION: In patients with COPD and severe exercise limitation, HFNO delivered by a battery-supplied portable device was more effective in improving walking distance than usual oxygen supplementation.

Multicenter randomized controlled trial comparing digital and traditional chest drain in a VATS pulmonary lobectomy cohort: interim analysis.

BACKGROUND: The usefulness of digital chest drain is still debated. We are carrying out a study to determine if the use of a digital system compared with a traditional system reduces the duration of chest drainage. To evaluate safety, benefit, or futility of this trial we planned the current interim analysis. METHODS: An interim analysis on preliminary data from ongoing investigator-initiated, multicenter, interventional, prospective randomized trial. Original protocol number: (NCT03536130). The interim main endpoint was overall complications; secondary endpoints were the concordance between the two primary endpoints of the RCT (chest tube duration and length of hospital stay). We planned the interim analysis when half of the patients have been randomised and completed the study. Data were described using mean and standard deviation or absolute frequencies and percentage. T-test for unpaired samples, Chi-square test, Poisson regression and absolute standardized mean difference (ASMD) were used. P-value < 0.05 was considered significant. RESULTS: From April 2017 to November 2018, out of 317 patients enrolled by 3 centers, 231 fulfilled inclusion criteria and were randomized. Twenty-two of them dropped out after randomization. Finally, 209 patients were analyzed: among them 94 used the digital device and 115 the traditional one. The overall postoperative complications were 35 (16.8%) including prolonged air leak (1.9%). Mean chest tube duration was 3.6 days (SD = 1.8), with no differences between two groups (p = 0.203). The overall difference between hospital stay and chest tube duration was 1.4 days (SD = 1.4). Air leak at first postoperative day detected by digital and traditional devices predicted increasing in tube duration of 1.6 day (CI 95% 0.8-2.5, p < 0.001) and 2.0 days (CI 95% 1.0-3.1, p < 0.001), respectively. CONCLUSIONS: This interim analysis supported the authors' will to continue with the enrollment and to analyze data once the estimated sample size will be reached. TRIAL REGISTRATION: Trial registration number NCT03536130 , Registered 24 May 2018 - Retrospectively registered.

Risk Factors for Olfactory and Gustatory Dysfunctions in Patients with SARS-CoV-2 Infection.

INTRODUCTION: Smell and taste loss are characteristic symptoms of SARS-CoV-2 infection. The aim of this study is to investigate the prevalence and risk factors associated with olfactory and gustatory dysfunctions in coronavirus disease (COVID-19) patients. METHODS: We conducted an observational, retrospective study on 376 patients with documented SARS-CoV-2 infection admitted to the San Gerardo Hospital in Monza, Italy, from March to July 2020. All patients answered a phone questionnaire providing information on age, sex, smoking status, and clinical characteristics. Adjusted odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated through logistic regression models including relevant covariates. RESULTS: The prevalence of olfactory and gustatory dysfunctions in COVID-19 patients was 33.5 and 35.6%, respectively. Olfactory dysfunctions were significantly directly associated with current smoking and history of allergy, the multivariable ORs being 6.53 (95% CI 1.16-36.86) for current smokers versus never smokers, and 1.89 (95% CI 1.05-3.39) for those with an allergy compared to those without any allergy. Respiratory allergy in particular was significantly associated with olfactory dysfunctions (multivariable OR 2.30, 95% CI 1.02-5.17). Significant inverse associations were observed for patients aged 60 years or more (multivariable OR 0.33, 95% CI 0.19-0.57) and hospitalization (multivariable OR 0.22, 95% CI 0.06-0.89). Considering gustatory dysfunctions, after allowance of other variables a significant direct association was found for respiratory allergies (OR 2.24, 95% CI 1.03-4.86), and an inverse association was found only for hospitalization (OR 0.21, 95% CI 0.06-0.76). CONCLUSION: Our study indicates that current smoking and history of allergy (particularly respiratory) significantly increase the risk for smell loss in COVID-19 patients; the latter is also significantly associated to taste loss. Hospitalization has an inverse association with the risk of olfactory and gustatory dysfunctions, suggesting that these may be symptoms characteristics of less severe SARS-CoV-2 infection.

Data about performances of whole and monovalent half-fragments antibodies in immunosorbent assays.

The data here presented are related to the research article entitled "Sensitivity and reproducibility enhancement in enzyme immunosorbent assays based on half fragment antibodies" [1] aimed to compare the performance in ELISA of whole antibodies and their corresponding monovalent half-fragments obtained by reduction. Half-fragment antibodies represent an interesting method to orient antibodies in high-sensitive immunoassays taking advantage of the free sulfhydryl groups of the hinge region [2], [3], [4] that allow their oriented binding on maleimide functionalized microplates. Data here presented describe the contribution of both chemical reduction and orientation on the antigen binding capacity of whole and half-fragments antibodies. For this purpose, monoclonal anti-horseradish peroxidase (anti-HRP) or monoclonal anti-fPSA antibodies, and their respective half-fragments, were coated on polystyrene or maleimide functionalized microplates. The antigen binding capability was analyzed by in-house enzyme linked immunosorbent assays. These data would be used for further studies on the development of oriented immunoassays based on half fragment antibodies.

Sensitivity and reproducibility enhancement in enzyme immunosorbent assays based on half fragment antibodies.

The free sulfhydryl groups of the hinge region of monovalent antibody fragments (rIgG) allow the orientation of rIgG on functionalized surfaces in immunosensors. To evaluate the contribution of reduction and orientation on signal enhancement we compared the performance of whole antibodies and their rIgG in ELISA performed on polystyrene or maleimide-functionalized microplates. Monoclonal anti-horseradish peroxidase (anti-HRP) and monoclonal anti-fPSA antibodies (1 mg/mL) were reduced with 2-mercaptoethylamine (53 mM). Western blot confirmed the presence of rIgG as a band at 75 kDa, detectable only by anti-heavy chain but not by anti-light chain antibodies, suggesting a possible folding rearrangement. Using anti-HRP we confirmed the retention of the antigen binding capacity of rIgG. Moreover, we observed a signal enhancement for rIgG even if randomly absorbed on polystyrene [linear regression slope (95%CI): rIgG 0.524 (0.434-0.614), IgG 0.370 (0.430-0.399); P = 0.0016] suggesting that chemical reduction might affect the antigen binding capacity of antibodies. ELISA with anti-fPSA rIgG coated on polystyrene confirmed these observations. Oriented anti-fPSA rIgG on a maleimide surface showed comparable signals to the assay performed on polystyrene for each analyzed concentration of antigen (PANOVA = 0.1980), anyway, with a significant improvement of the repeatability likely providing a more homogeneous capturing surface (SD rIgGmaleimide-rIgGpolystirene: fPSA 0.725 ng/mL:0.74-2.89; 1.45 ng/mL:1.56-8.69; 3.625 ng/mL:3.52-15.03; 7.25 ng/mL:7.78-18.44).

Evaluación del impacto de la cuarentena por la pandemia de COVID-19 en la transmisión perinatal del VIH en Buenos Aires, Argentina / Assessment of the impact of the COVID-19 pandemic lockdown on perinatal HIV transmission in Buenos Aires, Argentina

Objetivos: Describir variables epidemiológicas clave durante el año 2020 (pandemia de COVID-19) con respecto a la prevención de la transmisión perinatal (TP) del VIH en Ciudad de Buenos Aires (CABA), comparando con períodos previos.Métodos: Análisis retrospectivo de los datos agregados de TP de las principales maternidades de CABA. El año pandémico (2020) se comparó con los años no pandémicos 2018 y 2019.Resultados: Se observó una reducción del total de nacimientos en 2020 en comparación con 2019 y 2018 (11.640 vs. 14.031 y 15,978, respectivamente). La proporción de nacidos vivos en madres VIH+ (MEV) fue 0,88% en 2020, sin diferencia con 2019 y 2018 (0,94% y 0,93%), p> 0,05 para todas las comparaciones. Entre las MEV, el diagnóstico intraparto fue del 2,9% para 2020, sin diferencias con 2019 (2,25%) y 2018 (9,3%), p> 0,05 (todas las comparaciones); el 8,8% comenzó el tratamiento antirretroviral con > 28 semanas de edad gestacional en 2020 frente al 16% y el 18,05% en 2018 y 2019 (p> 0,05, todas las comparaciones). La prevalencia de la carga viral indetectable en el momento del parto fue del 67% en 2020 frente al 64% en 2018 y del 65,4% en 2019 (p> 0,05, todas las comparaciones). La transmisión perinatal fue 0% en 2020 vs. 1,33% en 2018 y 2,25% 2019 (p> 0,05, todas las comparaciones).Conclusiones: En la primera ola de la pandemia de COVID-19 no se observaron cambios en la proporción de MEV asistidas, diagnóstico intraparto de VIH, inicio tardío del TARV y TP en CABA

Background: To describe key epidemiological variables in 2020 (COVID-19 pandemic) regarding prevention of mother-to-child transmission (MTCT) in Buenos Aires city (CABA) in comparison with previous periods. Methods: Retrospective analysis of aggregated MTCT data was gathered from six principal maternity hospitals in Buenos Aires city. Pandemic year (2020) was compared to non-pandemic years 2018-19 individually considering key epidemiological variables. Results: A reduction of total births was observed in 2020 compared to 2019 and 2018 (11640 vs. 14031 and 15978, respectively). Proportion of live births in HIV-infected women (HPW) was 0.88% in 2020 without difference with 2019 and 2018 (0.94% and 0.93%), p> 0.05 for all comparisons. Among HPW, intrapartum diagnosis was 2.9% for 2020, with no difference between 2019 (2.25%) and 2018 (9.3%), p>0.05 (all comparisons); 8.8% had antiretroviral therapy (ART) started > 28 weeks of gestational age in 2020 vs. 16% and 18.05% in 2018 and 2019 (p> 0.05, all comparisons). Prevalence of undetectable viral load at delivery was 67% in 2020 vs 64% in 2018 and 65.4% in 2019 (p> 0.05, all comparisons). Perinatal transmission was 0% in 2020 vs 1.33% in 2018 and 2.25% 2019 (p> 0.05, all comparisons) Conclusions: In first wave of COVID 19 pandemic no changes in the proportion of HPW assisted, HIV intrapartum diagnosis, late ART initiation and MTCT-rate was observed in CABA

Unraveling HIV-1 diagnosis in special pediatric cases.

BACKGROUND: Early HIV-1 diagnosis and initiation of antiretroviral treatment is essential to prevent AIDS, and reduce mortality in children. HIV-1 molecular diagnosis in children before 18 months of age require, two independent samples to confirm a result. However, some patients have discordant virologic results in different samples, raising uncertainty for a conclusive diagnosis. We defined these patients as "special pediatric cases". OBJECTIVES: The aim of our study was to characterize the "special pediatric cases" among HIV-1 infected children diagnosed in a five-year period at our laboratory and evaluate the impact on the time to HIV-1 diagnosis. STUDY DESIGN: A total of 44 perinatally HIV-1 infected infants with molecular diagnostic performed at the Pediatric Garrahan Hospital were analyzed from 2013 to 2017. RESULTS: We identified eight "special pediatric cases". In the first samples, all of them had negative results by different DNA-PCR assays. Three infants had undetectable plasma viral load (pVL), four had low detectable pVL value, and one infant had no available pVL. All samples with detectable pVL, including those with low pVL (ie: 65copies/mL), had high pVL values at the end of the diagnosis. Considering the age of the HIV-1 infected children at the end of the diagnosis, five "special pediatric cases" (62 %) had a "late" positive diagnosis [mean (range) = 146 (89-268) days old]. CONCLUSIONS: These "special pediatric cases" are not as unusual as previously thought and are important diagnostic challenges. Also, this study add evidence to include the viral load assay in the molecular diagnostic algorithm for perinatal HIV-1 infection.

Italian suggestions for pulmonary rehabilitation in COVID-19 patients recovering from acute respiratory failure: results of a Delphi process.

There is a need of consensus about the pulmonary rehabilitation (PR) in patients with COVID-19 after discharge from acute care. To facilitate the knowledge of the evidence and its translation into practice, we developed suggestions based on experts' opinion. A steering committee identified areas and questions sent to experts. Other international experts participated to a RAND Delphi method in reaching consensus and proposing further suggestions. Strong agreement in suggestions was defined when the mean agreement was >7 (1 = no agreement and 9 = maximal agreement). Panelists response rate was >95%. Twenty-three questions from 4 areas: Personnel protection equipment, phenotypes, assessments, interventions, were identified and experts answered with 121 suggestions, 119 of which received high level of concordance. The evidence-based suggestions provide the clinicians with current evidence and clinical experts opinion. This framework can be used to facilitate clinical decision making within the context of the individual patient. Further studies will evaluate the clinical usefulness of these suggestions.

Respiratory physiotherapy in patients with COVID-19 infection in acute setting: a Position Paper of the Italian Association of Respiratory Physiotherapists (ARIR).

Respiratory physiotherapy in patients with COVID-19 infection in acute setting: a Position Paper of the Italian Association of Respiratory Physiotherapists (ARIR) On February 2020, Italy, especially the northern regions, was hit by an epidemic of the new SARS-Cov-2 coronavirus that spread from China between December 2019 and January 2020. The entire healthcare system had to respond promptly in a very short time to an exponential growth of the number of subjects affected by COVID-19 (Coronavirus disease 2019) with the need of semi-intensive and intensive care units.

Early-Middle Pleistocene benthic turnover and oxygen isotope stratigraphy from the Central Mediterranean (Valle di Manche, Crotone Basin, Italy): Data and trends.

Ostracod faunal turnover and oxygen isotope data (foraminifera) along the Valle di Manche (VdM) section are herein compiled. Specifically, the material reported in this work includes quantitative palaeoecological data and patterns of ostracod fauna framed within a high-resolution oxygen isotope stratigraphy (δ18O) from Uvigerina peregrina. In addition, the multivariate ostracod faunal stratigraphic trend (nMDS axis-1 sample score) is calibrated using bathymetric distributions of extant molluscs sampled from the same stratigraphic intervals along the VdM section. Data and analyses support the research article "Dynamics of benthic marine communities across the Early-Middle Pleistocene boundary in the Mediterranean region (Valle di Manche, Southern Italy): biotic and stratigraphic implications" Rossi et al. [1].

Kinetics study on recombinant alkaline phosphatase and correlation with the generated fluorescent signal.

Alkaline phosphatase (AP) (EC 3.1.3.1) is one of the most commonly used enzymes in immunoassays. In VIDAS® assays (bioMérieux, Marcy l'Etoile, France), AP catalyzes the hydrolysis of 4-methylumbelliferyl phosphate (4-MUP) in 4-methylumbelliferone (4-MU) producing a fluorescent signal. This work introduces an original method of characterization of the kinetic parameters Km, Vmax, and Kcat of AP embedded in VIDAS® assays. Assessment of such constants allows us to predict the fluorescent signal generated for given amounts of enzyme and its associated substrate; in the particular case of VIDAS®, it has been estimated that 0.06 nmol/L of AP produces 3144 Relative Fluorescent Values (RFV). ABBREVIATIONS: 4-MUP, 4-Methylumbelliferyl phosphate; 4-MU, 4-Methylumbelliferone; RFV, Relative Fluorescent Values; RFU, Relative Fluorescent Units; QDs, Quantum Dots; LoD, Limit of Detection.

Fluorescence enhancement aided by metal ion displacement.

Immunosensors are one of the most common platform used in clinical laboratories, in particular the class based on Enzyme Linked Fluorescent Assays (ELFA) takes advantage of the amplification step of the enzyme, usually the alkaline phosphatase, that catalyzes the hydrolysis of a fluorescent substrate leading it to fluoresce. Anyway, they suffer in sensitivity if compared to molecular diagnostic or more modern in vitro diagnostic devices. In our work, a simple and effective mechanism to enhance the fluorescent signal, and hence the sensitivity of the system, is presented. It is based on the metal ion displacement principle in which a second fluorophore, in our case Calcein Blue, quenched by a cobalt ion is add to the first one (4-MUP), and, in presence of inorganic phosphate, it will be progressively activated by the inorganic phosphate itself leading to the metal displacement. In this way Calcein Blue, newly free to fluoresce, contributes to global fluorescent signal generated by 4-MU. We have tested our proof of principle on a currently used immunoanalyzer, that is VIDAS® system (bioMérieux, Marcy l'Etoile, France) obtaining a fluorescence enhancement of about 50% for each concentration of hydrolyzed 4-MUP tested.

Ventilator Settings to Avoid Nuisance Alarms During Mouthpiece Ventilation.

BACKGROUND: A recent study found that activation of disconnection and low-pressure alarms is common during mouthpiece ventilation and may represent a major limitation to its use. The aim of this bench study was: (1) to investigate the technical aspects that can influence the setting of the ventilator during mouthpiece ventilation and (2) to provide a practical setting strategy to avoid the alarm activation. METHODS: Eight life-support ventilators able to deliver volume controlled ventilation were tested in a bench study using a single-limb non-vented circuit configuration connected to a standard mouthpiece. Disconnection and apnea alarm were turned off or set at the least sensitive setting. The backup frequency was set at the lowest available level. Different tidal volumes (VT) (from 500 to 1,200 mL) were tested with the rectangular and descending flow shape. For each VT, we reported the maximum set inspiratory time (TI) that allowed preventing activation of the low-pressure alarm. The presence of auto-triggering was also surveyed. RESULTS: We found that a correct combination of VT and TI avoided the activation of disconnection and low-pressure alarms in all but 3 ventilators. One ventilator did not allow mouthpiece ventilation independently from the settings used. The inability to turn off the apnea alarm in two other ventilators led to the alarm going off in any tested conditions after 120 s without triggered breaths. Auto-triggering was seldom found and easily worked out, except for in one ventilator. CONCLUSIONS: An appropriate alarm setting and combination of VT and TI would allow the majority of the tested ventilators to be used for mouthpiece ventilation without alarm activation.

Fotoprotección en la infancia / Photoprotection in childhood

La radiación ultravioleta (UV) es sólo una parte de las radiaciones electromagnéticas emitidas por el sol y tiene un especial interés dermatológico por los diversos efectos que causa sobre la piel. En este trabajo analizamos los distintos tipos de radiaciones, su participación en los procesos de bronceado y de fotoenvejecimiento y carcinogénesis e intentamos recomendar sencillas medidas de protección solar para que puedan llevar a cabo padres y niños. Si bien hoy en día la exposición solar, el desarrollo de la vida al aire libre y el hecho de estar bronceado son aspectos saludables, creemos que como pediatras jugamos un rol importante en la educación para la fotoprotección